The invention relates to a microsurgical microscope system with a stand and with a microscope arranged thereon, in which the stand has: a base part, a first substantially vertical parallelogram linkage, of which one bar of the substantially vertical bars is mounted on the base part so as to pivot about a pivot axle, a second substantially horizontal parallelogram linkage with two substantially horizontal bars and two further bars, of which one substantially horizontal bar is a continuation of the upper substantially horizontal bar of the first parallelogram linkage, and a mounting device for the microscope being arranged on the first further bar arranged at a distance from the first parallelogram linkage, and a third substantially vertical parallelogram linkage whose first lower hinge on the pivot axle of one of the substantially vertical bars of the first parallelogram linkage is connected to the base part, and whose second lower hinge is likewise connected to the base part and is connected via its upper bar to the second parallelogram linkage.
For operations on fine biological structures, in particular for neurosurgical operations on the brain and spinal cord, but also in the ENT field, operating microscopes are used which are arranged on easily movable stands near the operating site.
Depending on the type of operation, operating microscopes and stands of different size and design are used. In neurosurgery, systems have proven particularly useful in which the stand has weights which, in the manner of a balance, compensate the weight of the operating microscope. However, since the microscope has to be moved in the three spatial directions, the stand must have at least three axes of movement. While one axis can be arranged vertically and for this reason no weight compensation has to take place around this axis, it is necessary to effect the balance about two axes by changing the weights or moving the weights.
A great many examples of such stands can be found in the patent literature. In particular, U.S. Pat. No. 5,528,417 describes a system in which the microscope weight is compensated by a counterweight which is moved along a curve depending on the weight of the microscope. In this system, the holder for the microscope is additionally held horizontally by connecting bars, so that the microscope is always suspended vertically under the holder.
In the aforementioned microscope system, the second and the third parallelogram linkages are connected via a lever to two branches which enclose an angle of 90xc2x0. The lower branch is always held horizontally, and the upper branch is always held vertically. This admittedly results in quite a large pivot range for the second parallelogram linkage and, consequently, for the microscope arranged thereon. However, in the normal position when the second parallelogram forms a rectangle, the second parallelogram is horizontal, so that the operator may strike his head against it. For this reason, in the prior art it is necessary for the substantially horizontal bars to be arranged higher up or for them to be curved away from the operating site.
The object of the invention is to create a microscope system which is very user-friendly while at the same time affording more space for the operating surgeon.
The solution according to the invention lies in the fact that the second lower hinge of the third parallelogram linkage is arranged higher than the first, and in that the connection line between first and second hinges forms with the horizontal an angle of 30xc2x0 to 60xc2x0, and in that the upper bar of the third parallelogram linkage forms the second further bar of the second parallelogram linkage.
In this case, the bar of the second parallelogram linkage which is in proximity to the first and third parallelogram linkages is not vertical, but instead inclined at an angle of approximately 30xc2x0 to 60xc2x0, preferably 45xc2x0, so that in this normal position the second parallelogram linkage is directed obliquely upwards and the operating surgeon has room below this.
Depending on the operation, the operating microscope requires different additional parts which change the weight of the microscope. The system must therefore be balanced again after the microscope has been adapted.
However, the regularly required weight compensation has disadvantages. Upon compensation of the shift in weight, the range of compensation is limited and, if appropriate, has to be extended by arranging additional weights on the stand. In the case of automatic balancing, a high level of electromechanical input is required, which considerably increases the costs of a system. If it is forgotten to carry out the balancing procedure, this results in inconvenience for the surgeon and even a risk to the patient as a result of uncontrolled movements of the microscope.
For the reasons stated, the microscopes are equipped with all the necessary accessory parts, even when these are not needed for an operation. In this way, it is possible to avoid the balancing procedure which is carried out before the operation and the possible associated risk of imbalance. The disadvantage, however, is that the microscope system is rendered large and unwieldy by the many accessory parts and impedes the view of the operating field.
The above disadvantages can be avoided if, according to the invention, provision is made that a receiving device for accessory parts of the microscope and/or additional weights is connected to the first further bar of the second parallelogram linkage.
The invention makes use of the knowledge that because of the particular construction of this microscope system the balancing does not change if the weight acting on the second parallelogram linkage does not change. This weight does not change, however, if parts of the microscope, which is connected to the first further bar of the second parallelogram linkage, are removed and are arranged in or on the receiving device for the accessory parts, which is likewise connected to the first further bar of the second parallelogram linkage. The fact that the distance of these objects from the base part or any of the hinges of the parallelogram linkage changes, which change would cause different rotational moments, surprisingly plays no role here. This is due to the fact that, even upon swiveling of the parallelogram linkage, the orientation of the first further bar of the second parallelogram linkage and of the microscope and accessory parts arranged thereon does not change.
Accessory parts which are not required at a given time do not therefore impede the work with the microscope because they can be removed from the microscope and can be arranged in or on the receiving device for accessory parts, where they no longer obstruct the work with the microscope. The corresponding parts do not have to be carried through the operating theatre and in particular taken to other rooms, which would entail the risk of these parts being damaged, mislaid or contaminated. A new balancing procedure after exchange of an accessory part is not necessary. Instead, the balancing procedure can be carried out once for a defined microscope and for a defined set of accessory parts. No automatic balancing devices of any kind are required any longer. In this way, the stand as a whole can be made lighter, smaller and less expensive.
In some circumstances, the accessory parts for the microscope take up a relatively large amount of space, so that it can be difficult to accommodate them at the end of the second parallelogram linkage in the receiving device. In this case, a receiving device for accessory parts of the microscope and for additional weights can be provided on the base part. For each accessory part in this case, an equally heavy additional weight is provided which, if it is made of solid metal for example, obviously takes up a much smaller volume than the accessory part. If the relatively large-volume accessory part is not needed, it can be accommodated in the receiving device on the base part, where there is sufficient space. In its place, the substantially smaller additional weight is then arranged in the receiving device at the outer end of the second parallelogram linkage near the microscope.
Electrically or pneumatically releasable brakes are expediently arranged on hinges and/or the pivot axle. These brakes are released only if the stand is to be adjusted, that is to say the microscope is to be moved to another position.
After all the necessary accessory parts and the corresponding additional weights are arranged in the receiving device on the second parallelogram linkage or on the microscope, this microscope system can be equilibrated. This is expediently done by weights which can be arranged on the parallelogram linkages, in particular on the first parallelogram linkage. This balancing can be carried out once by a technician or by a theatre nurse for a given system, and it can be retained as long as the additional devices for the microscope are not replaced by others.
A particularly expedient configuration is characterized in that the bars of the parallelogram linkages are pipes which are held in bushings which form parts of the hinges and/or of the pivot axle. The hinge axles and/or the pivot axle can be arranged in the bushings outside the longitudinal axis of the pipes. To create more space for the operating surgeon, at least one bar of the parallelogram linkage can be curved in the direction away from the operating site.
The base part will expediently rest on the floor and can be provided in a manner known per se with lockable castors. However, it could also be arranged, for example, on the wall or on the ceiling of the operating theatre. The base part expediently has a foot part and a column which is pivotable about a vertical shaft and on which the further parts of the stand are then arranged.
However, the main feature of the invention is that, when the stand is swiveled, the angle at which the microscope and the receiving device for the accessory parts are oriented does not change. If the total weight of the microscope and of the accessory parts which are arranged on the microscope or on/in the receiving device does not change, the balance is maintained.